Just opened yesterday, black stuff (scrub-bable) all over the bottom after 24 hours pump run

ShinDiors

Well-known member
Jul 16, 2021
233
Northern VA
Pool Size
20500
Surface
Plaster
Chlorine
Liquid Chlorine
We are in Northern VA, and a newly replastered pool since last summer. The first season was alright and we learned a lot about the TFP protocol and handled our water chemistry ourselves.

Had pool company to close and open for the first time. New DE filter grid installed too. Pool was under safety cover since Nov, added some algaecide and chlorine during the winter, but soon had to drain out about 2-3 inches prior to a freezing event. Water was filled back up mostly by rain and we refilled about maybe one inch back to the skimmer level.

Pool company did brushing and vacuum (not through our pump), added 3 lbs of granular chlorine and half gallon acid. CYA was below 20 so we were OK to put in four pucks in floater. They used the same Tyler testing kit recommended here. We tested the water in the evening, FC was 9.5, TA 70, CA 200, PH 7.4.

We noticed a few hours after the pool company left that there were black stuff scattered around the bottom. They are clustered in somewhere, other places more scattered, also scrubbable like regular dust.

Our temperature has been jumping past week, highest reaching 86, but lowest at 35. Next couple of days will be in 30s/50s. I guess algae probably could not survive in this temperature?

Questions for you veteran pool owners, what could be these scrubbable black stuff? I do have a main drain at deeper end floor, so do I just treat them like regular dust and use brush to push them towards main drain, then vacuum?

The water otherwise becomes very clear already.

Thanks a lot.
 
Another question, we currently do not have heater and it is too cold to swim. I plan to cover the pool with solar cover in another day or two, and let it breathe once in a while. We did that last fall and did not run into problems. When the pool opens, do I want to keep it uncovered for longer ?(concern is pollen here).
 
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